CVE-2026-55103
Discourse ActivityPub adds ActivityPub support to Discourse
- Risk score
- 58/100
- CVSS
- 8.6 v3.1
- Exploit chance (30 days)
- 0.2%
- Published
- 15 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can …
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 8.6 high
- Remotely exploitable without logging in
References
Original description
Discourse ActivityPub adds ActivityPub support to Discourse. Prior to commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5, inbound ActivityPub processing does not sufficiently verify that the actor authenticated by the signed request matches the Activity actor and owns the referenced federated post. A remote attacker can exploit these missing identity and ownership checks to edit, delete, or reply to federated posts without the required permissions. This vulnerability is fixed with commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5.
Last activity 15 Oct 2026. Patch Forecast updates every hour.